Iran has virtually halted a previously rapid expansion of its uranium enrichment capacity in the past three months, the U.N. nuclear agency said in a report roughly covering the period since moderate Hassan Rouhani became president.
The quarterly report by the International Atomic Energy Agency (IAEA) also showed that Iran's stockpile of higher-grade enriched uranium - closely watched by the West and Israel - had risen by about 5 percent to 196 kg since August.
But it remained below the roughly 250 kg needed for a bomb if refined further. Iran denies Western and Israeli accusations that it is seeking nuclear weapons capability, saying it is enriching uranium only for peaceful energy.
The quarterly IAEA report - scrutinised by Western governments - was the first that included developments only since Rouhani took office on Aug. 3, prompting a diplomatic opening during which Iran and six world powers have made progress towards ending a standoff over its nuclear activity.
The IAEA said Iran had installed only four first-generation centrifuges - machines used to refine uranium - at its Natanz plant since August, making a total of 15,240. In the previous three-month period, May-August, it installed more than 1,800. Not all of the installed centrifuges are operating.
Rouhani, a pragmatist, succeeded bellicose hardliner Mahmoud Ahmadinejad in August, promising to try to settle the decade-old nuclear dispute and secure an easing of sanctions that have severely damaged Iran's oil-dependent economy.